Virtually, any well which produces liquid hydrocarbons, such as crude oil, also produces a residual amount of natural gas and water. In the normal production or drilling facility, low pressure vent gas, if presently in a limited quantity, is discharged into the atmosphere rather than being saved or otherwise used for commercial purposes.
In the instance of offshore producing facilities, this residual gas is dissipated into the air by way of one or more flare booms which extend outwardly from the offshore structure. A flare boom is normally furnished to each offshore platform such that vented gas is carried away from the platform by prevailing wind, rather than being blown back onto the structure.
The term vent gas as herein utilized refers to that portion of the gas which is raised from a producing operation, but is at an insufficient pressure and/or insufficient quantity to warrant being conserved.
Since this residual natural gas is combustible and normally combustion supporting, it can constitute a danger to the platform from both a safety consideration as well as a health consideration for the workers.
Once the gas enters the atmosphere it usually becomes sufficiently diluted to be safe from further ignition. Even so, the gaseous mixture formed at the flare boom discharge port can be readily ignited into an open flame by natural causes, such as by a flash of lightening. Offshore platforms or structures are normally isolated in a body of water. It stands to reason that in the event of an electrical storm, the accompanying lightning could constitute a flame-triggering medium for the vented gaseous mixture.
As a matter of practicality, in the Gulf of Mexico it is not an uncommon event for the vented gas to be ignited by lightning during an electrical storm. To extinguish the resulting flame, however, often constitutes a difficult procedure due to the flare boom structure extending outwardly over the water, and the lack of a convenient mechanism for extinguishing the flame. Further, flare booms are normally installed at an elevated angle of about 30.degree. such that the vent gas stream will be released in an upward direction.